my 175 runs out of steam??????

[smoore-gt225]

hi my series 2 tuned 175 runs great upto 55 then it seems to stall if you know what i mean, it feels like not reaching its potential
ive been told its probaly the gearbox as its a standard li 125 with 15-46 sprockets
now ive been told to change the front sprocket to a 16 or 17
any advice on what sprocket to change to would be gratefully received
exhaust is a 42mm clubman and carb is a 28 spaco open mouth
cheers in advance
steve

[Monty]

Gearing is not quite as simple as changing sprockets
You say you run out of steam at 50 I presume in 4th.
You need to try and judge how its reving through all gears.
With a standard pipe you are going to max out at around 6K revs with your gearing thats good for MPH in 4th, 41 in 3rd.
If you find it revs higher in 3rd than 4th, you will loose power when going up hill or into strong winds if you increase the front sprocket.
If its pulling well in 4th but just maxed out then a 17 x 46 will give you 61 in 4th.
I would go the exhaust route myself, I have just fitted a JL curly on my series 1 and it revs far higher than it ever did.
An extra 500 revs on your setup will have you at just under 60
The 28mm Carb is a bit OTT IMHO I would fit a 22 mm Jetex and save some petrol.

[soullad]

I would have thought that your set up would be able to pull a 16 tooth front sprocket.
Try it out on the road, and see if it improves?

[DaveTomo]

don't know if this may help http://www.tonycassidy.com/Gearbox_Visualiser.html

[Donnie]

Smoore, you're running out of steam in 4th aren't you?

You're scoots screaming it's nuts off when you get there isn't it?

I already know that the answer is yes mate as you have exactly what I had about 10 years ago on my S2 LI125 when I put my 175 kit on.(other than the carb, but that's not the problem here)

Yes is the short and simple answer, a 16t front sprocket on your set up is exactly what you need as it will raise the gearing and not have it screaming in 4th.

As for the carb, if its working leave it be unless it's using a huge amount of juice more than your mates with jetex's.

I'm loath to contradict people but I would have thought putting a JL on as Monty suggests will indeed allow it to rev out more but you're problem is that it's already revving out on the clubman, keeping the clubman, which is a nice torquey pipe will ensure you won't have any noticable probs on hills at all with such a small change.

One thing, you'll need a stretched 80 link chain for 16/46 but with luck your chain may already accomodate this.

[smoore-gt225]

hi thanks for replies ive fitted a 16 tooth sprocket and it seems to pull a little better now
cheers steve

[Monty]

Smoore, you're running out of steam in 4th aren't you?

You're scoots screaming it's nuts off when you get there isn't it?

I already know that the answer is yes mate as you have exactly what I had about 10 years ago on my S2 LI125 when I put my 175 kit on.(other than the carb, but that's not the problem here)

Yes is the short and simple answer, a 16t front sprocket on your set up is exactly what you need as it will raise the gearing and not have it screaming in 4th.

As for the carb, if its working leave it be unless it's using a huge amount of juice more than your mates with jetex's.

I'm loath to contradict people but I would have thought putting a JL on as Monty suggests will indeed allow it to rev out more but you're problem is that it's already revving out on the clubman, keeping the clubman, which is a nice torque pipe will ensure you won't have any noticable probs on hills at all with such a small change.

One thing, you'll need a stretched 80 link chain for 16/46 but with luck your chain may already accomodate this.

Contradict away, I'm big enough and daft enough to take it.
The original question that no one answered, was that it ran out of steam, it didn't say screaming its head off. If his engine has the torque he can pull a 19 front sprocket as I did on my Casa but I doubt he will pull it. A 16 or 17 would be better. I have spent months messing with my Muggy kit, and the JL has been the best investment I have made, Revs = speed, in my case a 150 Indian box required no changes, even with the 3rd 4th jump, a 125 box is a great box but may do.
I don't want to be contentious but personally a stretched chain has only one home, the bin